Should the FTC have allowed Zillow to acquire its foremost rival, Trulia? It is increasingly well-accepted that digital platforms tend toward dominance in their immediately adjacent relevant-product markets. Google, for example, has long held a majority share of the markets for general-search...

The internet giants – Facebook, Amazon, Apple, Microsoft, and Google – have transformed society with both positive and negative effects. The negative effects have been stark. There have been huge disruptions caused by e-commerce. More recently, subtler, but even more serious negative effects...

Recent claims that online platforms have secured permanent monopolies, protected by barriers to entry from network effects and stockpiles of data, and should be the focus of intense antitrust and regulatory scrutiny, are inconsistent with the economics, technology, and history of online...

Many Internet intermediaries operate two-sided networks, that is, they provide platforms to bring together two types of participants, or quot;sides,quot; such as buyers and sellers. This paper develops a model that characterizes the intermediary's pricing in two-sided networks, the value created...

The internet giants - Facebook, Amazon, Netflix and Google, among others - have transformed society with both positive and negative effects. The negative effects have been stark. There have been huge disruptions caused by e-commerce. More recently, subtler, but even more serious negative effects...

We study the welfare effects of a merger between ad-funded platforms facing elastic consumer demand. We show that advertising fees as well as quality investment levels by the platforms fall post-merger. Interestingly, despite the lower advertising fees, advertisers may be worse off when their...

When a consumer can appear on both sides of a two-sided market, such as a user who both buys and sells on eBay, the platform may want to bundle the services it provides to two sides. I develop a general model for such "mixed" two-sided markets, and show that a monopolist platform's incentive to...

We study the incentives of a monopolistic hybrid platform in sharing its superior market information with the third-party seller hosted on its marketplace. After observing platform information-sharing policy, the seller competes in prices with the platform over a horizontally differentiated...

Fee discrimination is commonly used by marketplace platforms (e.g., Amazon, eBay, and Uber). To better understand how marketplace fee discrimination interacts with the hybrid platform business model, we model a marketplace platform that manages fees and categories across a continuum of retail...

Platforms often use fee discrimination within their marketplace (e.g., Amazon, eBay, and Uber specify a variety of merchant fees). To better understand the impact of marketplace fee discrimination, we develop a model that allows us to determine equilibrium fee and category decisions that depend...